Tookayerta Creek, near Mount Compass
2010 Aquatic Ecosystem Condition Report
- Permanently wet, flowing, freshwater creek in autumn and spring
- Highly diverse macroinvertebrate community with many rare and sensitive species
- Obvious signs of moderate nutrient enrichment
- Riparian vegetation mostly consisted of introduced woody weeds and grasses and some native gums and reeds
About the location
Tookayerta Creek is a moderately large stream in the southern Mount Lofty Ranges, rising south of Mount Compass and flowing east where it ultimately discharges into the Finniss River. The major land use is cattle grazing, with minor areas of native vegetation and rural residential living also present.
The monitoring site was located off Cleland Gully Road, about four kilometres south-east of Mount Compass.
The creek was given a Very Good rating because the site sampled showed evidence of very little change in ecosystem structure and function. There was evidence of human disturbance, including nutrient enrichment and weedy riparian zones, although the stream still provided an important refuge for many macroinvertebrate species. The widespread grazing of stock and limited cover of remnant native vegetation indicates that the condition of the stream could potentially be downgraded in the future if nutrient loads to the creek increase in the future due to poor land management practices, or if flow reduces due to water extraction or climate effects.
A highly diverse community of about 40 species of macroinvertebrates was collected from the flowing creek, 2-3 metres wide and up to 80 centimetres deep, in autumn and spring. A small amount of fast-flowing riffle habitat was present in spring but the stream was mostly a slow-flowing channel in 2010.
The community consisted of a range of species tolerant to poor water quality as well as many sensitive and rare species. Large numbers of amphipods (Austrochiltonia australis), chironomids, caddisflies (Triplectides) and blackfly larvae were collected; the latter dominated the community in spring. The community also included smaller numbers of snails (including the introduced Physa and Potamopyrgus antipodarum), worms, mites, isopods, springtails, beetles, dixid fly larvae, biting midges, mayflies, waterbugs, stoneflies and caddisflies. Several sensitive or rare species were collected from the site, including blackfly larvae (Paracnephia), three mayflies (Atalophlebia, Koorrnonga inconspicua and Tasmanophlebia), three stoneflies (Illiesoperla mayi, Leptoperla tasmanica and Austrocerca tasmanica) and five caddisflies (Taschorema, Ulmerochorema, Lingora, Atriplectides dubius and Triplectides similis). Several species normally associated with flowing water were also collected, including three species of blackflies (Paracnephia, Austrosimulium furiosum and Simulium ornatipes), a chironomid (Rheotanytarsus) and many of the above-listed mayflies, stoneflies and caddisflies.
The water was fresh (salinity of 171 mg/L), well oxygenated (79-95% saturation) and slightly coloured in spring, with moderate to high concentrations of nutrients such as nitrogen (0.55-1.0 mg/L) and phosphorus (0.04-0.1 mg/L).
The sediments were dominated by detritus, sand and silt; samples taken from below the surface were black and anaerobic in spring, indicating too much organic matter had accumulated in the sediments. A deposit of 1-5 centimetres of silt covered the creekbed in spring.
Only small amounts of phytoplankton and filamentous algae (Spirogyra) were recorded from the site in 2010. Over 10% of the channel was covered by aquatic plants, including a range of floating (Azolla and Spirodela) and emergent species (Phragmites, Isolepis, Polygonum, introduced Rorippa, Cotula, Cyperus, Juncus and Rumex).
The riparian zone and surrounding terrestrial vegetation mostly consisted of introduced weedy plants such as introduced grasses, blackberries, ash and willow trees, and native species such as reeds (Phragmites), bracken and gum trees.
Special environmental features
Tookayerta Creek provides a significant habitat for several sensitive and rare species of macroinvertebrates, and a range of flow-dependent species. Many of these are particularly sensitive to disturbances and have highly restricted distributions in the region and State. The mayfly from the Family Oniscigastridae (Tasmanophlebia), for example, has only been collected from Tookayerta Creek and three other creeks from the Fleurieu Peninsula in South Australia.
Recent fish surveys in the catchment have also recorded the presence of at least three threatened fish species (Mountain Galaxias, River Blackfish and Southern Pygmy Perch) from the mid to lower sections of the creek (M. Hammer, Aquasave Consultants, 2009).
Pressures and management responses
|Livestock have direct access at the site and upstream, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).||The SA Murray–Darling Basin NRM Board acknowledges the significant impacts that livestock have on aquatic environments and seeks to provide free technical advice and incentives to land managers for fencing and other works as funding permits. Funding incentives are limited in value and extent and require land managers to volunteer to be involved.|
|Limited riparian vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The SA Murray–Darling Basin NRM Board recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.|
|Insufficient natural water flows resulting from water extraction and climate variability (reducing ecological integrity.||The SA Murray–Darling Basin NRM Board is working with the Department for Water and the community to develop a water allocation plan and licensing system which aim to balance social, economic and environmental needs for water. The objective for providing water to the environment is to maintain and/or restore self-sustaining water-dependent ecosystems which are resilient in times of drought.|
|Widespread introduced trees and weeds in the riparian zone at the site and upstream in the catchment (reducing habitat quality).||The SA Murray–Darling Basin NRM Board recognises the limitations of available funds relative to the scale of the degradation caused by introduced trees and weeds. The NRM Board provides free technical advice and community education to assist land managers in dealing with the integrated management of aquatic weeds. The NRM Board also has a targeted process, as directed by State Government, to strictly prioritise its investment in weed control activities as funds are limited. The NRM Board actively seeks funding opportunities for weed control; most opportunities are for locations where biodiversity outcomes can be achieved.|
|Feral predatory fish (trout and redfin) (reducing ecological integrity)||Local volunteer groups are undertaking works at some sites. The SA Murray–Darling Basin NRM Board opportunistically removes pest fish during monitoring activities. Other agencies are responsible for the control of pest fish and have undertaken some awareness-raising activities throughout the region.|